Method of cleaning filter-leaves.



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PAUL FOSTER LEACH, 0F WOLLASTON, MASSACHUSETTS, ASSIGNOR T0 MOORE FILTERCOMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

' METHOD OF CLEANING FILTER-LEAVES.

No Drawing.

To all whom, it may concern Be it known that I, PAUL FosTER LEAcH, acitizen of the United States, residing at Wollaston, in the county ofNorfolk and State of Massachusetts, have invented certain new and usefulImprovements in Methods for Cleaning Filter-Leaves, of which thefollowing is a specification.

My invention relates to a method for cleaning filter leaves used forfiltering solutions in ore-treating processes, and partlcularly in thetreatment of ores containing precious metals by the cyaniding process.

It is well known that in the process of treating ores containingprecious metals by the cyaniding process, lime is used in order toprevent the destruction of the cyanid by the acids in the solution andin the process of filtering the solution the lime cakes or crystallizesupon the filter leaves and in the interstices of the fabric forming thesame so as to interfere with the free passage of the liquids through thefabric.

The object of the present invention is to provide a method by which thelime adhering to the filter leaves may be quickly and thoroughly removedwithout in any way injuring the filter leaves or altering theirformation so as to interfere with the subsequent proper filtration ofsolutions.

In practising my invention I employ lactic acid which may be either inits commercial form or diluted with water, applying the lactic acid, orits solution, directly to the fabric of the filter leaves so as to comeinto direct and intimate contact '-with the lime which may adherethereto. The acid upon coming into contact with the lime completelydissolves the same from the surface ofthe fabric and from theinterstices of the latter so that the lime in solution is thoroughlyremoved from the fabric.

In treating the leaves, according to my invention, I preferably employ atank either of wood or wood-lined, so as not to be affected by the acid,and into which the acid is placed, preferably in a solution in theproportion of approximately one pound of commercial lactic acid, whichis of twenty-two per cent. strength, to twenty-five pounds of water, andin this solution immerse the leaves until the lime carried therebypasses into solution. The action of the lactic acid upon the lime may beaccelerated and the time of treatment shortened by heating theSpecification of Letters Patent.

lliaten'ted June 350, 1914.

Application filed October 25, 1911. Serial No. 656,776.

solution in any suitable manner. I have found that the process will bequickly and thoroughly performed if the solution is heated up toapproximately one hundred and fifty degrees Fahrenheit, more or less.The time of treatment necessary to cleanse the leaves of the lime is, ofcourse, dependent largely upon the strength of the solution and thetemperature at which it is used, but a solution of the proportions oflactic acid and water described will thoroughly cleanse the leaves inless than an hour and, when heated to the temperature set forth, willperform the cleansing operation in less than one-half hour.

From actual performance of the method above described I find that thelactic acid in no waydestroys, injures or renders brittle the fabric orthe fibers of which it is composed and, in fact, acts as a preservativeof the same, maintaining the fiber at all times soft and flexible. Thelactic acid also has no astringent effect on the fibers tending toshrink the same and thereby enlarge the interstices of the fabric andthereby destroy its properties as a filtering medium. In other words, asfar as I have been able to judge from actual tests, the use of thelactic acid has no objectionable or deleterious effect on the fabricwhatever.

It will be understood that I do not desire to be limited to the exactmethod of treatment set forth either as to proportions, temperature, ortime of treatment, as these all may vary, within the scope of myinvention, according to the different circumstances under which themethod is to be practised.

What I claim and desire to secure by Letters Patent of the United Statesis l. The method of removing lime from a filter fabric which consists insubjecting the fabric to lactic acid.

2. The method of removing lime from a filter fabric which consists insubjecting the fabric to a solution of lactic acid and water.

3.The method of removing lime from a filter fabric which consists insubjecting the fabric to a solution of lactic. acid and water in theproportion of approximately one pound of lactic acid to twenty-fivepounds of water.

4. The method of removing lime from a filter fabric which consists insubjecting the filter fabric to the action of lactic acid in thepresence of heat.

5. The method of removing lime from a filter fabric which consists insubjecting the filter fabric to the action of lactic acid in thepresence of heat up to approximately one 5 hundred and fifty degreesFahrenheit.

6. The method of removing lime from a fiiter fabric which consists insubjecting the fabric to a solution of lactic acid in the proportion ofone pound of twenty-two per 10 cent. lactic acid to twenty-five poundsof water heated up to approximately one hundred and fifty degreesFahrenheit.

In testimony whereof I have hereunto signed my name in the presence oftwo subscribing Witnesses.

PAUL FOSTER LEACH.

Witnesses:

M. E. MCNINCH, C. G. HEYLMAN.

